JavaScript is a dynamic, weakly-typed language typically used for client-side scripting. Use this tag for questions regarding ECMAScript and its various dialects/implementations (excluding ActionScript). Unless a tag for a framework/library is also included, a pure JavaScript answer is expected.

HTML (HyperText Markup Language) is the standard markup language used for structuring web pages and formatting content. HTML describes the structure of a website semantically along with cues for presentation, making it a markup language, rather than a programming language. The most recent revision to the HTML specification is HTML5.

JSON (JavaScript Object Notation) is a 100% textual data interchange format originally inspired by JavaScript objects. It is widely used in RESTful web services. Parsers for JSON exist in nearly all languages, and libraries also exist which can deserialize JSON to native objects or serialize native objects to JSON.